1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly to a face discharge type plasma display panel.
2. Description of the Prior Art
Plasma display panels, which utilize a gaseous discharge phenomenon, basically include DC type plasma display panels in which selection of pixels is provided by two groups of electrodes arranged in such a manner that they intersect with each other while facing each other. However, such DC type plasma display panels exhibit low luminance because they exhibit a delayed discharge initiation while performing a discharge operation only when desired pixels are selected. For this reason, it is impossible to display moving pictures in a high resolution using DC type plasma display panels.
In order to achieve a rapid discharge initiation and a memory effect (namely, a continued discharge even when no pixel is selected), a variety of plasma display panels have been proposed. For example, AC type plasma display panels and hybrid plasma display panels have been proposed.
In Face discharge type plasma display panels which are a kind of AC type plasma display panels, a discharge operation is initiated between facing electrodes. After the discharge initiation, the discharge is maintained by adjacent electrodes arranged on the same substrate. Accordingly, such face discharge type plasma display panels obtain a high luminance, as compared to conventional plasma display panels in which a discharge occurs mainly at intersections of electrodes.
Referring to FIG. 1, a general configuration of a face discharge type plasma display panel is shown. As shown in FIG. 1, the face discharge type plasma display panel includes a pair of spaced substrates P1 and P2 respectively having electrodes E1 and E2. The electrodes E1 and E2 are arranged in such a manner that they intersect with each other while facing each other. A dielectric layer I is formed over the substrate P1 in such a manner that the electrodes E1 formed on the substrate P1 are buried in the dielectric layer I. A fluorescent layer F is formed over the substrate P2 in such a manner that the electrodes E2 formed on the substrate P2 are buried in the fluorescent layer F. In FIG. 1, the reference character "R" denotes partitions for partitioning pixels.
The plasma display panel includes at least two electrodes E1 (namely, E1a and E1b) buried in the dielectric layer I. Where the plasma display panel includes two maintenance electrodes E1a and E1b, it is called a "three-electrode type plasma display panel". Where the plasma display panel includes three maintenance electrodes, it is called a "four-electrode type plasma display panel".
In such a face discharge type plasma display panel, one of the maintenance electrodes E1a and E1b generates an initial discharge along with the electrode E2 facing the maintenance electrodes. Following this initial discharge, a maintenance discharge occurs between the maintenance electrodes E1a and E1b. Thus, a continued discharge is achieved. Accordingly, this face discharge type plasma display panel exhibits high luminance because the discharge is maintained with high luminous strength for a lengthened period of time.
However, conventional face discharge type plasma display panels have several problems to be solved.
Where the fluorescent layer F is to be formed on the front substrate P1, it should have the form of a thin filter. In this case, accordingly, there is a difficulty in the fabrication. Where a plurality of maintenance electrodes are formed on the rear substrate P2 on which partitions R are also formed, the rear substrate P2 has a very complex structure. For this reason, reflection type plasma display panels have been generally used in which the maintenance electrodes E1 and dielectric layer I are formed on the front substrate P1 whereas the fluorescent layer F is formed on the rear substrate P2.
In this structure, however, the front substrate P1, which are directed to the eyes of the user, are partially shielded by the dielectric layer I and the maintenance electrodes E1a and E1b. This results in a great decrease in the open area ratio of this structure. As a result, it is impossible to obtain a great enhancement in luminance, in spite of an enhancement in luminous strength. In particular, although the four-electrode type plasma display panel including three maintenance electrodes employs a luminance enhancing configuration involving a complexity in configuration and a great increase in the manufacturing costs, it obtains a luminance only slightly higher than that obtained in the three-electrode type plasma display panel.
Basically, the maintenance discharge carried out between the maintenance electrodes in the conventional face discharge type plasma display panel is an AC discharge carried out through the dielectric layer I. In other words, the maintenance discharge is not directly carried out between the two maintenance electrodes E1a and E1b. A process, which involves the steps of forming wall charge on the surface of the dielectric layer I and generating a kind of electron avalanche, is repeatedly carried out between the maintenance electrodes in order to supply charge into a discharge space. Thus, a plasma discharge occurs.
As apparent from the above description, the conventional face discharge plasma display panel has an operation principle in which its two maintenance electrodes E1a and E1b, between which the dielectric layer I is interposed as shown in FIG. 2, form a capacitor, thereby generating a kind of AC discharge. Therefore, this face discharge plasma display panel may be considered to be a capacitive coupling plasma display panel.
As well known, AC discharge does not exhibit a high discharge strength. For this reason, the conventional face discharge type plasma display panel obtains a low plasma density of about 10.sup.10 /cm.sup.2. This value corresponds to only several times the ionization rate of AC type plasma display panels. Furthermore, such a capacitive coupling plasma display panel forms a capacitor having a large capacitance by itself. As a result, a great increase in parasitic capacitance occurs. This interferes with a rapid driving of the panel.